WO2021017464A1

WO2021017464A1 - Grating-based infrared touch-control screen system

Info

Publication number: WO2021017464A1
Application number: PCT/CN2020/076900
Authority: WO
Inventors: 叶志成; 傅翼斐
Original assignee: 上海交通大学
Priority date: 2019-07-31
Filing date: 2020-02-27
Publication date: 2021-02-04
Also published as: CN110502145A

Abstract

A grating-based infrared touch-control screen system. The system comprises an optical stylus, an information display layer, a spectrum filtering optical film, a grating, a waveguide layer and a light receiver. The optical stylus simultaneously emits visible light and invisible light onto a touch-control screen, the visible light is used for marking a touch-control position, and the invisible light of a specific wavelength is diffracted by the grating on the waveguide layer to form invisible light in a waveguide mode that can be transmitted in a waveguide, and is transmitted to the light receiver as touch-control detection light; and the spectrum filtering optical film has the functions of reflecting visible light and transmitting invisible light, and can reduce diffraction by a large-period grating, without affecting display light. In the present invention, it is not necessary to additionally provide a camera, thereby saving on costs. The detection light is invisible light, thereby improving the user experience of human-computer interaction.

Description

Infrared touch screen system based on grating

Technical field

The invention relates to an interactive touch technology in the field of information display technology, in particular to an infrared touch screen system based on a grating.

Background technique

With the popularization of various terminals, human-computer interaction methods have also emerged. As the first contact medium between terminals and people, display screens are also developing, and they are widely used in teaching, conferences, games and other scenarios. According to different technical principles, touch control has four variable sensing methods: acoustic, optical, electrical, and pressure. Of these four technologies, most of them can only perform contact touch, and cannot perform remote non-contact touch, such as electrical resistive screens and capacitive screens, pressure-type pressure sensing screens, and acoustic surface acoustic wave screens. , Optical active light source infrared screen. Most of the touch screen systems that can achieve both contact type and non-contact type need to add a camera system to the above-mentioned contact type screen system to perform image recognition of human-computer interaction touch positions.

Camera-style human-computer interaction, although it satisfies non-contact touch, it still has shortcomings. First, the range of human activities is limited to the recognition range of the camera, and the body posture is required, and the recognition target cannot be arbitrarily blocked; second , When used by multiple users, it increases the difficulty of recognition and limits the range of activities, which also brings inconvenience to human-computer interaction; third, the cost of adding cameras and real-time image processing systems is higher.

Currently, there is an optical waveguide type optical touch screen based on a grating structure and a compensation light source (Patent Application No. 201510220923.2). Although infrared light is mentioned as detection light, the infrared light is used as an active light source for contact Type destruction does not involve long-distance non-contact touch interaction. At the same time, there is a problem that when infrared light is used as the detection light, the period of the coupling grating is relatively large, which results in strong grating diffraction. If there is no visible light filtering before the grating , Will be unable to view due to diffraction.

Summary of the invention

The purpose of the present invention is to provide a grating-based infrared touch screen system in view of the above-mentioned shortcomings of the prior art. The infrared touch screen system integrates contact and non-contact touch while also saving costs and improving The advantage of user experience.

The technical solution of the present invention is as follows:

A grating-based infrared touch screen system, which is characterized by including an optical stylus, a display information layer, a spectral filter optical film, a grating, an optical waveguide layer, and a light receiver. The display information layer and the spectral filter optical The film, the grating, and the optical waveguide layer constitute the touch screen. The optical stylus simultaneously emits visible light and invisible light of a specific wavelength to the touch screen. The invisible light of the specific wavelength can be The grating diffracts into the invisible light of the waveguide mode that can be transmitted in the optical waveguide layer, and is transmitted to the light receiver as the touch detection light, which is converted into the current signal of the display position.

The optical stylus simultaneously emits visible light and invisible light of a specific wavelength, the visible light is used to mark the touch position, and the invisible light of the specific wavelength is used as the touch detection light.

The display information layer is a projected reflective screen or a non-projected display layer.

The spectral filter optical film has the functions of reflecting the visible light and transmitting the invisible light respectively.

The spectral filter optical film is placed on a side of the display information layer away from the user, and is attached or not attached to the display information layer.

The material of the optical waveguide layer is a single layer material or a multilayer material that is transparent to invisible light, and the refractive index of the material of the optical waveguide layer is single or graded.

The optical waveguide layer is placed on the side of the spectral filter optical film away from the user and is attached or not attached to the spectral filter optical film; if attached, the refractive index of the material of the optical waveguide layer is not less than The refractive index of the spectral filter optical film.

The size of the period of the grating covering the optical waveguide layer satisfies that at least one invisible light emitted by the optical stylus becomes the waveguide detection light.

The grating is covered on any side of the optical waveguide layer or placed in the optical waveguide layer.

The wavelength range of the visible light wavelength is 380 nm to 780 nm, and the wavelength range of the invisible light wavelength of the specific wavelength is above 780 nm.

The optical receiver is a sensor array capable of detecting the wavelength of the invisible light and is placed on the periphery of the optical waveguide layer.

The spectral filtering optical film has the functions of reflecting visible light and transmitting invisible light, and can reduce the diffraction of the large-period grating without affecting the display information layer and the touch detection light. The invention utilizes the coupling characteristic of the grating to couple the invisible light of a specific wavelength emitted by the optical stylus to the optical waveguide layer to form the detection light, and the light receiver determines the change in the intensity of the detection light.

Compared with the prior art, the beneficial effects of the present invention are as follows:

The present invention uses an optical stylus to emit visible light and invisible light. The visible light is used to mark the touch position. The invisible light of a specific wavelength is diffracted by the grating on the touch screen into a waveguide mode that can be transmitted in the waveguide, and is transmitted to the The light receiver is used as the touch detection light; contact and non-contact touch can be realized without additional camera recognition system, saving costs; the use of the spectral filter optical film does not affect the display effect, but reduces The influence of the diffracted light of the large-period grating on the user.

Description of the drawings

Figure 1 shows the theoretical value diagram of the coupling grating period for infrared wavelengths above 800 nm.

Figure 2 is a graph of the simulated value of the coupled grating period corresponding to infrared wavelengths above 800 nm.

Figure 3 is a schematic diagram of the coupling efficiency of optical stylus with a wavelength of 532nm visible light and a wavelength of 808nm invisible light at a grating period of 650nm

4 is a schematic structural diagram of Embodiment 1 of the infrared touch screen system based on a grating of the present invention.

5 is a schematic cross-sectional structure diagram of Embodiment 1 of the infrared touch screen system based on a grating of the present invention.

FIG. 6 is a three-dimensional schematic diagram of the embodiment 1 of the infrared touch screen system based on the grating in the projection system as a reflective screen.

FIG. 7 is a schematic diagram of the structure of Embodiment 2 of the infrared touch screen system based on the grating in the non-projection mode of the present invention.

Detailed ways

The present invention will be described in detail below in conjunction with embodiments and drawings, but the protection scope of the present invention should not be limited by this.

The +m-level and -m-level coupling formulas of the grating waveguide are shown in formula (1). Among them, k ₀ is the wave number in vacuum, n ₀ is the refractive index of the incident medium, θ is the angle of incidence in the waveguide, T is the grating period, n ₁ is the waveguide refractive index, and n _eff is the effective refractive index of the waveguide. In the absolute value part of formula (1), the +m-order diffracted light takes a positive sign, and the -m-order diffracted light takes a negative sign. And there is m=0,±1,±2..., n ₁ >n ₀ ,

According to the simplification of formula (1), to make the +m-order diffracted light become the waveguide mode in the waveguide, the following conditions should be met:

In the same way, the m-order diffracted light should meet the following conditions:

Among them, λ is the wavelength of invisible light incident in vacuum.

When the incident angle θ and grating period T are determined, it is obvious that only invisible light wavelengths in the incident light satisfy the above formula (2) and formula (3), and at least the same order (±m,0), (0, The series of ±m) and (+m,-m) meet the coupling condition, and the light of other series will be emitted through the grating waveguide.

In fact, the grating period T slightly smaller than the theoretical value can also meet the requirements. The wavelength range that the human eye can perceive is 380nm to 780nm, and the wavelength range of infrared is 760nm to 1mm. According to the above theory, for the visible and invisible light emitted by the optical stylus, we can set the appropriate grating period ( As shown in Figure 1, Figure 2), consider the ±1st order diffracted light, make the infrared invisible light of 780nm and above become the waveguide mode, and set the visible light from 380nm to 780nm that cannot be coupled into the corresponding grating period to mark the touch position. In this way, while not affecting the touch screen display, we use light with invisible wavelengths as the detection light, which also improves the user experience. For example, under approximately normal incidence, ie θ∈(0°,1°), the incident medium is air n ₀ =1, the waveguide medium is plastic n ₁ =1.59, λ ₁ ＝530nm, λ ₂ ＝808nm, grating period T = 650nm, the simulation result is shown in Figure 3. It can be seen that almost no light is coupled in the waveguide at 530nm, and 10% of light is coupled in the waveguide at 808nm.

The present invention is based on the projection display system, through the combined use of the optical waveguide layer covering the grating and the spectral filter optical film, while using infrared light as the detection light, it also reduces the user experience of the diffracted light of the large period grating Impact.

Example 1

Please refer to Figure 4 and Figure 5. 4 is a schematic structural diagram of Embodiment 1 of the infrared touch screen system based on a grating of the present invention. 5 is a schematic diagram of the cross-sectional structure of the projection system in Embodiment 1 of the grating-based infrared touch screen system of the present invention. As can be seen from the figure, the grating-based infrared touch screen system of the present invention includes an optical stylus 201, a display information layer 202, a spectral filter optical film 203, a grating 204, an optical waveguide layer 205 and a light receiver 206, which are composed of The display information layer 202, the spectral filter optical film 203, the grating 204, and the optical waveguide layer 205 constitute a touch screen. The light receiver 206 is placed on the periphery of the optical waveguide layer 205, and the optical stylus 201 simultaneously emits visible light and invisible light of a specific wavelength to the touch screen. The invisible light of the specific wavelength can be diffracted by the grating 204 on the optical waveguide layer 205 into the light The invisible light of the waveguide mode transmitted in the waveguide layer 205 is transmitted to the light receiver 206 as the touch detection light, and converted into a current signal of the display position.

The optical stylus 201 is used by touch screen users. The shape and material of the optical stylus 201 are not limited. The light source of the optical stylus 201 is composed of visible light and invisible light. The display information layer 202 may be a projected reflective screen or a non-projected display layer. The spectral filter optical film 203 is not limited in material, and only needs to satisfy the function of reflecting visible light while transmitting infrared invisible light. The optical waveguide layer 205 is placed on the side of the spectral filter optical film 203 away from the touch user. The optical waveguide layer 205 has a grating 204 on the side away from the user. Optical receivers 206 are provided around the optical waveguide layer 205. If the grating 204 faces the spectral filter optical film 203, it is made of a transparent material; if the grating surface of the optical waveguide layer 205 faces away from the optical film, an infrared reflective film can be coated to enhance the coupling efficiency of infrared light.

When working, the optical stylus 201 emits visible light and invisible light at the same time. First, the visible light is reflected by the spectral filter film 203 to mark the position of the user's interactive touch point, while the invisible light transmits through the spectral filter optical film 203 and passes through When grating 204, infrared light of a certain wavelength enters the optical waveguide layer 205 and is transmitted laterally in the optical waveguide layer to become a waveguide mode. The optical receiver 206 detects the infrared light transmitted laterally in the optical waveguide 205 and constitutes an important part of touch detection. When the optical stylus 201 emits infrared invisible light, contact or remote non-contact can form a touch interaction with the infrared touch screen, and the positioning of the operating object is realized by the light intensity change detected by the light receiver 206.

It is particularly emphasized that when infrared light is used as the detection light, the period of the coupling grating is larger, which results in stronger diffraction light of the grating. If there is no visible light filtering by the spectral filter film 203 in front of the grating, it will be impossible to view due to diffraction. The spectral filter optical film 203 has the function of reflecting visible light and transmitting invisible light, which can reduce the diffraction of the large-period grating without affecting the display light.

FIG. 6 is a three-dimensional schematic diagram of Embodiment 1 of the grating-based infrared touch screen of the present invention as a reflective screen in a projection system. The optical stylus 201 is included for use by touch screen users. The shape and material of the optical stylus are not limited, and the light source is mainly composed of visible light and invisible light. The display information layer 202 is now a projected reflective screen for displaying projection information. The spectral filter optical film 203 satisfies the function of reflecting visible light and transmitting infrared invisible light. The optical waveguide layer 205 is placed on the side of the spectral filter optical film 203 away from the touch user. The optical waveguide layer 205 has a grating 204 on one surface. Optical receivers 206 are provided around the optical waveguide layer 205. If the grating 204 faces the spectral filter optical film 203.

When working, the optical stylus 201 emits visible light and invisible light at the same time. First, the visible light is reflected by the spectral filter film 203 to mark the position of the interactive touch point for the user and the audience, while the invisible light transmits through the spectral filter optical film 203. When passing through the grating 204, infrared light of a certain wavelength enters the optical waveguide layer 205 and is transmitted laterally in the optical waveguide layer to become a waveguide mode. The optical receiver 206 detects the infrared light transmitted laterally in the optical waveguide 205 and constitutes an important part of touch detection. When the optical stylus 201 emits infrared invisible light, contact or remote non-contact can form a touch interaction with the infrared touch screen, and the positioning of the operating object is realized by the light intensity change detected by the light receiver 206.

Example 2

FIG. 7 is a schematic structural diagram of Example 2 of an infrared touch screen based on a grating of the present invention, which is used in a non-projection display system. The display information layer 202 is a liquid crystal panel or an organic light-emitting layer at this time. The film 203 is attached to the side of the display information layer 202 away from the user. The optical stylus 201 is used by touch screen users. The shape and material of the optical stylus are not limited, and the light source is mainly composed of visible light and invisible light. The spectral filter optical film 203 satisfies the function of reflecting visible light and transmitting infrared invisible light. The optical waveguide layer 205 is placed on the side of the spectral filter optical film 203 away from the touch user. The optical waveguide layer 205 has a grating 204 on the side away from the user. Each group of adjacent sides of the transparent optical waveguide layer 205 is provided with a light receiver 206. If the grating 204 faces the spectral filter optical film 203, it is made of a transparent material.

The advantage of using the spectral filtering optical film 203 is that, without affecting the touch interaction, the influence of the large-period grating diffracted light on the display effect is greatly reduced, and the viewing experience of the user is improved.

Experiments show that the present invention utilizes the diffraction of the grating, the invisible light of a specific wavelength in the optical stylus becomes the detection light of the touch point, and the visible light serves as the mark position, so that the touch interaction does not affect the effect of the display system. In addition, the spectral filter film has the function of reflecting visible light and transmitting invisible light, which greatly reduces the diffracted light of the grating and brings a good user experience.

Claims

A grating-based infrared touch screen system, which is characterized by including an optical stylus (201), a display information layer (202), a spectral filter optical film (203), a grating (204), and an optical waveguide layer (205) The light receiver (206) is composed of the display information layer (202), the spectral filter optical film (203), the grating (204), and the optical waveguide layer (205) to form a touch screen. The light receiver (206) Placed on the periphery of the optical waveguide layer (205), the optical stylus (201) emits visible light and invisible light of a specific wavelength to the touch screen at the same time. Invisible light is invisible light that can be diffracted by the grating (204) into a waveguide mode that can be transmitted in the optical waveguide layer (205), and is transmitted to the optical receiver (206) as touch detection The light is converted into a current signal showing the position.
The grating-based infrared touch screen system according to claim 1, characterized in that the optical stylus (201) emits visible light and invisible light of a specific wavelength at the same time, and the visible light is used to mark the touch position and the specific wavelength The invisible light is used as the touch detection light.
The grating-based infrared touch screen system of claim 1, wherein the display information layer (202) is a projected reflective screen or a non-projected display layer.
The grating-based infrared touch screen system according to claim 1, wherein the spectral filter optical film (203) has the functions of reflecting the visible light and transmitting the invisible light respectively.
The grating-based infrared touch screen system according to claim 1, wherein the spectral filter optical film (203) is placed on the side of the display information layer (202) far away from the user, and is connected to the display information layer (202). (202) Fit or not fit.
The grating-based infrared touch screen system according to claim 1, wherein the material of the optical waveguide layer (205) is a single-layer material or a multilayer material that is transparent to invisible light, and the optical waveguide layer The refractive index of the material of (205) is single or graded.
The grating-based infrared touch screen system according to claim 1, characterized in that the optical waveguide layer (205) is placed on the side of the spectral filter optical film (203) far away from the user, and the spectral filter optical film (203) Bonded or not bonded; if bonded, the refractive index of the material of the optical waveguide layer (205) is not less than the refractive index of the spectral filter optical film (203).
The grating-based infrared touch screen system according to claim 1, characterized in that the period of the grating (204) covering the optical waveguide layer (205) is sufficient to make the optical stylus (201) emit At least one of the invisible light becomes the waveguide detection light.
The grating-based infrared touch screen system according to claim 1, wherein the grating (204) is covered on any side of the optical waveguide layer (205) or placed on the optical waveguide layer ( 205) in.
The grating-based infrared touch screen system according to any one of claims 1 to 9, wherein the wavelength range of the visible light wavelength is 380nm to 780nm, and the wavelength range of the invisible light wavelength of the specific wavelength is Above 780nm.